diff --git a/test/test_animations.ml b/test/test_animations.ml
index 2da8b23fc..f4be7d943 100644
--- a/test/test_animations.ml
+++ b/test/test_animations.ml
@@ -200,15 +200,9 @@ let test_theme_animation_sorts_by_name () =
    space, so a keyframe name carrying an underscore of its own is written [\_]
    and keeps the character. *)
 let test_shorthand_underscore_escape () =
-  let css cls =
-    match Tw.of_string cls with
-    | Ok u -> Tw.to_css ~base:false [ u ] |> Tw.Css.to_string
-    | Error (`Msg m) -> Alcotest.failf "%s: %s" cls m
-  in
-  Alcotest.(check bool)
-    "an escaped underscore stays in the keyframe name" true
-    (Astring.String.is_infix ~affix:"animation: wiggle_x 1s infinite"
-       (css {|animate-[wiggle\_x_1s_infinite]|}))
+  Test_helpers.check_declarations ~minify:false
+    {|animate-[wiggle\_x_1s_infinite]|}
+    [ "animation: wiggle_x 1s infinite" ]
 
 let tests =
   [
diff --git a/test/test_divide.ml b/test/test_divide.ml
index f72e92651..05ba89496 100644
--- a/test/test_divide.ml
+++ b/test/test_divide.ml
@@ -56,20 +56,21 @@ let test_arbitrary_width_roundtrip () =
   check "divide-x-[1rem]";
   check "divide-y-[0.5rem]";
   check "divide-x-[0.5rem]";
-  let selector cls =
+  (* The whole selector. An affix of it says the class name appears somewhere,
+     which [.divide-x-\[1rem\]x] would satisfy too; what this test is about is
+     that each width names its own rule. *)
+  let selects cls sel =
     match Tw.of_string cls with
-    | Ok u -> Tw.to_css ~base:false [ u ] |> Tw.Css.to_string ~minify:true
     | Error (`Msg m) -> Alcotest.failf "%s: %s" cls m
+    | Ok u ->
+        Alcotest.(check bool)
+          (cls ^ " selects the class the author wrote")
+          true
+          (List.mem sel (Test_helpers.selectors_of_utility u))
   in
-  Alcotest.(check bool)
-    "divide-x-[1rem] selects the class the author wrote" true
-    (Astring.String.is_infix ~affix:".divide-x-\\[1rem\\]"
-       (selector "divide-x-[1rem]"));
+  selects "divide-x-[1rem]" {|:where(.divide-x-\[1rem\] > :not(:last-child))|};
   (* Two rem widths are two class names, not one. *)
-  Alcotest.(check bool)
-    "divide-x-[2rem] is its own class" true
-    (Astring.String.is_infix ~affix:".divide-x-\\[2rem\\]"
-       (selector "divide-x-[2rem]"))
+  selects "divide-x-[2rem]" {|:where(.divide-x-\[2rem\] > :not(:last-child))|}
 
 (* The typed constructor spells the width itself, and builds exactly the classes
    the bracket reader accepts. Tailwind takes a line-width keyword there -
diff --git a/test/test_flex_props.ml b/test/test_flex_props.ml
index 767841b5f..e965c572a 100644
--- a/test/test_flex_props.ml
+++ b/test/test_flex_props.ml
@@ -150,10 +150,12 @@ let test_basis_arbitrary_keeps_the_authored_spelling () =
       | Error (`Msg m) -> Alcotest.failf "%s: %s" cls m
       | Ok u ->
           Alcotest.(check string) "class round-trips" cls (Tw.pp u);
-          let css = Tw.to_css ~base:false [ u ] |> Tw.Css.to_string in
-          Alcotest.(check bool)
-            (cls ^ " selects itself") true
-            (Astring.String.is_infix ~affix:escaped css))
+          (* The whole selector list, which is where "names its rule with the
+             bracket text" is said: an affix of the selector is satisfied by a
+             longer one that starts the same way. *)
+          Alcotest.(check (list string))
+            (cls ^ " selects itself") [ escaped ]
+            (Test_helpers.selectors_of_utility u))
     [
       ("basis-[0.5ch]", {|.basis-\[0\.5ch\]|});
       ("basis-[0.0]", {|.basis-\[0\.0\]|});
diff --git a/test/test_interactivity.ml b/test/test_interactivity.ml
index c28915ccf..8b97ca399 100644
--- a/test/test_interactivity.ml
+++ b/test/test_interactivity.ml
@@ -115,15 +115,8 @@ let test_invalid_arbitrary_will_change () =
    The arbitrary value spells that one [\_], so the class both parses and keeps
    the character. *)
 let test_will_change_underscore_escape () =
-  let css cls =
-    match Tw.of_string cls with
-    | Ok u -> Tw.to_css ~base:false [ u ] |> Tw.Css.to_string
-    | Error (`Msg m) -> Alcotest.failf "%s: %s" cls m
-  in
-  Alcotest.(check bool)
-    "an escaped underscore stays in the property name" true
-    (Astring.String.is_infix ~affix:"will-change: a_b"
-       (css {|will-change-[a\_b]|}))
+  Test_helpers.check_declarations ~minify:false {|will-change-[a\_b]|}
+    [ "will-change: a_b" ]
 
 let tests =
   [
diff --git a/test/test_scroll.ml b/test/test_scroll.ml
index d6dc2e26d..00cf3b69d 100644
--- a/test/test_scroll.ml
+++ b/test/test_scroll.ml
@@ -46,13 +46,8 @@ let test_typed_prime () =
    is not a utility: it used to be reinterpreted as a variable name, so
    [scroll-m-[2vh]] emitted [scroll-margin: var(--2vh)]. *)
 let test_arbitrary_length () =
-  let css cls =
-    match Tw.of_string cls with
-    | Ok u -> Tw.to_css ~base:false [ u ] |> Tw.Css.to_string
-    | Error (`Msg m) -> Alcotest.failf "%s: %s" cls m
-  in
-  let emits affix cls =
-    Alcotest.(check bool) cls true (Astring.String.is_infix ~affix (css cls))
+  let emits decl cls =
+    Test_helpers.check_declarations ~minify:false cls [ decl ]
   in
   emits "scroll-margin: 2vh" "scroll-m-[2vh]";
   emits "scroll-padding-top: 3ch" "scroll-pt-[3ch]";
diff --git a/test/test_scrollbar.ml b/test/test_scrollbar.ml
index 2950e77be..edaca89c3 100644
--- a/test/test_scrollbar.ml
+++ b/test/test_scrollbar.ml
@@ -79,6 +79,9 @@ let test_transparent_keeps_its_keyword () =
         |> Tw.Css.to_string ~minify:true
     | Error (`Msg m) -> Alcotest.failf "scrollbar-thumb-transparent: %s" m
   in
+  (* The whole declaration, and it stays a search over this sheet rather than an
+     exact list: what is under test is what the optimizer above leaves, which
+     declarations_of_class does not run. *)
   Alcotest.(check bool)
     "the utility keeps the transparent keyword" true
     (Astring.String.is_infix ~affix:"--tw-scrollbar-thumb:transparent" css)
diff --git a/test/test_tables.ml b/test/test_tables.ml
index 53fcd2e90..1c8024275 100644
--- a/test/test_tables.ml
+++ b/test/test_tables.ml
@@ -19,20 +19,26 @@ let border_spacing_prime () =
    every other unit unparsed, and the class-name printer had a placeholder
    waiting to stand in for whatever it could not spell. *)
 let arbitrary_border_spacing () =
-  let css cls =
-    match Tw.of_string cls with
-    | Ok u -> Tw.to_css ~base:false [ u ] |> Tw.Css.to_string ~minify:true
-    | Error (`Msg m) -> Alcotest.failf "%s: %s" cls m
+  let shorthand =
+    "border-spacing:var(--tw-border-spacing-x) var(--tw-border-spacing-y)"
   in
-  let emits cls affix =
-    Alcotest.(check bool) cls true (Astring.String.is_infix ~affix (css cls))
+  (* The whole list. The affixes named one axis of a utility that sets both, and
+     never the shorthand that reads them. *)
+  let both cls value =
+    Test_helpers.check_declarations cls
+      [
+        "--tw-border-spacing-x:" ^ value;
+        "--tw-border-spacing-y:" ^ value;
+        shorthand;
+      ]
   in
-  emits "border-spacing-[123px]" "--tw-border-spacing-x:123px";
-  emits "border-spacing-[1rem]" "--tw-border-spacing-y:1rem";
-  emits "border-spacing-x-[2em]" "--tw-border-spacing-x:2em";
-  emits "border-spacing-y-[1.5vw]" "--tw-border-spacing-y:1.5vw";
-  emits "border-spacing-[calc(1rem_+_2px)]"
-    "--tw-border-spacing-x:calc(1rem + 2px)";
+  both "border-spacing-[123px]" "123px";
+  both "border-spacing-[1rem]" "1rem";
+  both "border-spacing-[calc(1rem_+_2px)]" "calc(1rem + 2px)";
+  Test_helpers.check_declarations "border-spacing-x-[2em]"
+    [ "--tw-border-spacing-x:2em"; shorthand ];
+  Test_helpers.check_declarations "border-spacing-y-[1.5vw]"
+    [ "--tw-border-spacing-y:1.5vw"; shorthand ];
   List.iter
     (fun cls ->
       Alcotest.(check string)